Every business day since taking the helm as the Postal Service’s top champion of “green,” Sam Pulcrano gets in his hybrid electric car at his home in a nearby Virginia suburb and commutes to USPS Headquarters in southwest Washington, DC.

The Postal Service has a long history of environmental stewardship, a fact not lost on the people who work there, so it’s a good bet that with 600,000 fellow employees, Pulcrano isn’t the only postal person driving an alternative fuel vehicle to work. And since USPS has the largest fleet of civilian vehicles in the world –– 217,000 –– it’s likely that some of those employees, especially if they are letter carriers, will get out of their personal green vehicle and step into one of the Postal Service’s 44,000 alternative fuel-capable delivery vehicles.